Hyoid bone position with bone-borne or tooth-borne surgically assisted rapid palatal expansion: a retrospective...

There is a lack of evidence whether hyoid bone position changes with surgically assisted rapid palatal expansion (SARPE), which could improve the airway. The aim of this study was to (1) evaluate the differences in hyoid bone position with SARPE, (2) assess whether there are differences between bone-borne or tooth-borne expansion appliances, and (3) investigate possible relationships between expansion values and hyoid bone position.

Eligible for inclusion in this retrospective cohort study were adult patients who underwent SARPE using bone-borne or tooth-borne expansion appliances. The Hyrax group (n=32; female/male 20/12; mean age 26.0 ± 9.1 years) was treated with a hyrax appliance and the TPD group (n=33; female/male 15/18; mean age 25.0 ± 8.0 years) was treated with a transpalatal distractor. The position of the hyoid bone was determined on lateral cephalograms before ([Formula: see text]) and after SARPE ([Formula: see text]) using eight measurements and five landmarks. Arch width was measured at dental landmarks on STL files and the amount of maxillary expansion was calculated.

Hyoid bone position remained generally stable, with changes not exceeding 2 mm. The only statistically significant change in the overall cohort was observed for the sagittal distance Hy-Me, which decreased from 44.23 mm to 43.40 mm ([Formula: see text]). Significant differences between groups were noted for the vertical distance Hy-Me', with the Hyrax group showing a mean change of -1.95 mm ([Formula: see text]) and the TPD group showing an increase of 0.75 mm ([Formula: see text]), while the craniocervical inclination α decreased by 1.25[Formula: see text] in the TPD group ([Formula: see text]). All other measurements showed no significant changes and possible correlations between the expansion values and the position of the hyoid bone were inconclusive.

While the results indicate small, statistically significant, but probably clinically negligible movements of the hyoid bone after SARPE, the hyoid position remained generally stable and changes were not dependent on the appliance used or the amount of expansion.

Overall, the observed changes were not substantial enough to support any clinically meaningful effects of SARPE on airway function through hyoid bone movements.